Trunk hunting circuit



Sept. 8, 1942.

`o. CESAREO TRUNK HUNTING CIRCUlT Filed Sept. 24, 1941 v .S E

/Nl/ENTOR Wp. CESAREO GP5. SWM- A7' 7' ORNE V Patented Sept. 8, 1942 oireo TES PATENT @ENCE TRUNK HUNTDIG CIRCUIT Application September 24, 1941, Serial No. 412,073

7 Claims.

. until their circuits are opened by a test relay which operates when an idle position is found.

It being desired to increase the speed of hunting, in accordance with the present invention busy or vacant positions are marked with ground and a self-interrupting circuit is provided for the stepping magnet in series with a polarized test relay, and the test wiper of the switch, the circuit being so arranged that the magnet operates when the test wiper rests on a busy or vacant position and the test relay operates when the test wiper engages an idle position. The test relay when operated controls means for opening the test circuit and marking the position busy, and locks independent of both the stepping magnet and the position circuit.

The invention will be more clearly understood from a consideration of the following description in connection with the drawing which shows a trunk circuit embodying the invention.

When the trunk is seized, a bridge is closed across conductors H0 and III, completing a circuit from battery through the upper winding of relay H6, contact 4 of relay H5, winding 2 of repeating coil H4, conductor H3, ring contacts of test jack |09, conductor over the bridge at the calling oiiice, conductor H0, tip contacts of test jack |09, conductor H2, winding of repeating coil H4, contact I of relay H5, lower winding of relay H6 to ground. Relay H6 operates in this circuit and grounds conductor |4|, operating relay |I'|. Ground on conductor |4| is extended over contact I of relay |40 to the sleeve of jack |99 and over contact 2 of relay |29 to lamp I I 9 and in parallel therewith over the auX- iliary contact of jack |09 to conductor |42 leading to the service observing position.

Relay I I! closes a circuit from a source of machine ringing current through ballast lamp H8, contact 4 of relay condenser |43, contact 6 of relay |29, through winding 4 of repeating coil I4, through the winding of relay |38 to battery and ground, as an indication to the calling subscriber that the information operator is being called.

Relay I|'| also connects ground over its contact 2, contact 5 of relay |29, contact I of relay |23, through resistance |44 to conductor |20 leading to the allotter. This circuit also extends over contacts and 2 of relay |23, contact 3 of relay |40 to conductor |2| to mark this trunk as calling to the sequence storing circuit.

The allotter functions, in response to the grounding of conductor |20, in the manner described in the above-identified Carpenter et al. patent Ito start an idle sequence storing circuit hunting for the calling trunk. After a storing circuit has connected with the trunk by means of the ground on conductor |2I, and has performed certain functions, a relay is operated which closes a locking circuit for itself between ground and conductor |22, thereby completing acircuit over Contact I of relay |29, and contact 3 vof relay to the winding of relay |23 and battery.

Relay |23 operates, disconnecting ground from conductor |20, thereby disconnecting the trunk from the allotter. However, the connection between the trunk and the storing circuit is maintained by the locking circuit above traced.

Relay |23 also disconnects groundfrom conductor .|2I and extends that conductor to the winding of relay |24 and battery.

As fully described in the above-mentioned patent, the storing circuits and associated trunks are seized one at a time by a start circuit which determines the order in which the trunks hunt for idle operators positions. When the start circuit :connects with the trunk it connects ground to conductor |2I, operating relay 24.

Relay |24 starts the position finder |00 hunting for an idle operators position. At contact 2 relay 24 closes a circuit from wipers |03 and '|06 over contact 5 of relay |21, windingof polarized relay |25, back contact andwinding of stepping magnet |01 to battery.

A portion of an operators position is shown connected to the rst 'terminals of wipers |0I, |02 and |03. When the position is vacant, ground is connected to conductor |45 over the back contact of relay |3I. When the position is occupied relay |3| is operated extending conductor |45 over the front contact of relay |3I, normal `cont-acts of hold key |32 and release key |33, back Contact of relay |34 to battery through the winding of relay |48. With key |32, key |33 or relay |34 operated the position is marked unavailable by the connection of ground to conductor |45.

At contact relay |24 connects ground through the winding of relay |26 to the operating circuit of magnet |01 between the winding of the magnet and the winding of relay |25.

If switch is resting on an idle position circuit, battery connected to conductor |45 will complete a circuit for polarized relay |25 in series with relay |26. Relay |25, being polarized to respond to the current now owing in this circuit, closes its left contact very rapidly, completing an obvious circuit for relay |21 which is also quick to operate. Relay |21 at contact 6 connects battery through resistance |28 to the winding of relay |25 to hold that relay operated. At contact 5, relay |21 disconnects the windings of relay |25 and magnet |01 from wiper |03 and at contact 4 connects ground to Wiper |03 to mark the position busy.

If switch |00 is resting on a busy position circuit, ground on conductor |45 completes the above traced circuit of magnet |01 which interrupts its own circuit to advance switch |00 in search of an idle position circuit. The current flowing through relay |25 at this time is in the reverse direction so that the relay remains unoperated. During hunting ground on conductor |45 shunts relay |25 preventing its operation. When an idle circuit is found relay |25 functions as above described.

If conductor |45 is accidentally opened so that neither ground nor battery appears on the terminal engaged by wiper |03,` the operation of relay |24 connects ground through the winding of relay |26 to the back contact and winding of magnet |01 and battery. Relay |26 is of high resistance and therefore magnet |01 cannot operate in series with it. Relay |26 is also slow to operate so that it cannot operate before relays |25 and |21 operate in connection with an idle position and is shunted as above mentioned when the position finder rests on` a busy position. When the position finder encounters a position having an open test conductor, relay |25 operates, closing a circuit from ground over the right contact of relay |25, contact 1 of relay |21, contact of relay |26 to the winding of magnet |01 and battery. Magnet |01 operates, opening the circuit of relay |26 which releases, in turn releasing magnet |01 and advancing switch |00 to the next position circuit.

It is apparent that this circuit arrangement provides high speed hunting since the polarized testing relay permits the switch to advance as fast as the mechanism will operate. In addition means is provided to prevent delays caused by one or more position nders stopping on contacts connected to open position test conductors until released by the maintenance force.

For further operation of this trunk circuit and the position circuit, reference may be had to the above-mentioned Carpenter et al. patent.

While the invention has been described in connection with the particular call distributing system described in the Carpenter et al. patent, it is clearly applicable to any trunk hunting circuit employing self-operated switches, and has been so claimed.

A related trunk hunting arrangement is disclosed and claimed in the application of C. G. Spencer, Serial No. 412,059, filed September 24, 1941.

What is claimed is:

1. In a telephone system, a switch, a magnet for causing said switch to advance in search of an idle trunk, a polarized relay, a test wiper for said switch, an operating circuit for said magnet including said polarized relay and said test wiper in series, means in busy trunks for operating said magnet over said circuit, means in idle trunks for operating said relay, and means under the control of said relay when operated by an idle trunk for stopping said switch and establishing a connection with said trunk.

2. In a telephone system, a switch, a magnet for causing said switch to advance in search of an idle trunk, a polarized relay, a test wiper for said switch, an operating circuit for said magnet including said polarized relay and said test wiper in series, means in busy trunks for operating said magnet over said circuit, means in idle trunks for operating said relay, and means under the control of said-relay when operated by an idle trunk for disconnecting said relay and said magnet from said test wiper.

3. In a telephone system, a switch, a magnet for causing said switch to advance in search of an idle trunk, a polarized relay, a test wiper for said switch, an operating circuit for said magnet including said polarized relay and said test wiper in series, means in busy trunks for operating said magnet over said circuit, means in idle trunks for operating said relay, and means under the control of said relay when operated by an idle trunk for marking said trunk busy and for disconnecting said relay and said magnet from said test wiper.

4. In a telephone system, a switch, a magnet for causing said switch to advance in search of an idle trunk, a polarized relay, a test wiper for said switch, an operating circuit for said magnet including said polarized relay and said test wiper in series, means in busy trunks for operating said magnet over said circuit, means in idle trunks for operating said relay and means under the control of said relay when operated by an idle trunk for marking said trunk busy and for locking itself independent of said magnet and said test wiper.

5. In a telephone system, a switch, a magnet for causing said switch to advance in search of an idle trunk, a polarized relay, a test wiper vfor said switch, a rst operating circuit for said magnet including said polarized relay and said test wiper, means in busy trunks for operating said magnet over said rst circuit, means in idle trunks for operating said relay, means under the control of said relay when operated by an idle trunk for disconnecting said relay and said magnet from said test wiper, an auxiliary relay, a second circuit for said magnet, means to operate said auxiliary relay when said test wiper rests on a trunk which does not complete said first circuit, and means under the control of said auxiliary relay for completing said second circuit.

6. In a telephone system, a switch, a magnet for causing said switch to advance in search of an idle trunk, a polarized relay, a test wiper for said switch, a i'lrst operating circuit for said magnet including said polarized relay and said test wiper, means in busy trunks for operating said magnet over said rst circuit, means in idle trunks for operating said relay, means under the control of said relay when operated by an idle trunk for disconnecting said relay and said magnet from said test wiper, an auxiliary relay, a second circuit for said magnet, means to operate said auxiliary relay when said test wiper rests on a trunk which does not complete said rst circuit, means under the control of said auxiliary relay to render said second circuit effective to operate said magnet, and means to operate said auxiliary relay and said magnet alternately until said test wiper reaches a trunk which completes said first circuit.

7. In a telephone system, a switch, a magnet for causing said switch to advance in search of an idle trunk, a polarized relay, a test wiper for said switch, a first operating circuit for said magnet including said polarized relay and said test wiper, means in busy trunks for operating said magnet over said first circuit, means in idle trunks for operating said relay, means under the control of said relay when operated by an idle trunk for disconnecting said relay and said magnet from said test wiper, an auxiliary relay, a second circuit for said magnet, means to operate said auxiliary relay when said test wiper rests on a trunk which does not complete said first circuit, means under the control of said auxiliary relay to render said second circuit effective to operate said magnet, means to operate said auxiliary relay and said magnet alternately until said test wiper reaches a trunk which completes said first circuit, and means to release said auxiliary relay when said last-mentioned trunk completes said first circuit.

ORFEO CESAREO. 

